1. Field of the Invention
The present invention relates to an actuator which is combined with a slide table and operable for displacing the slide table along a guide rail.
2. Description of the Related Art
Actuators coupled with slide tables are sometimes used to convey workpieces from one position to another position.
One conventional actuator with a slide table is shown in FIG. 5 of the accompanying drawings.
As shown in FIG. 5, an actuator 1 basically comprises a cylinder body 2 substantially in the shape of an elongate rectangular parallelepiped, a slide table 3 displaceable axially along the cylinder body 2, a piston rod 4 coupled to a piston (not shown) which is movably disposed in a bore that is defined in one side of the cylinder body 2, an end block 5 supporting a distal end of the piston rod 4 and coupled to an end of the slide table 3, and a linear guide 6 coupled to an upper surface of the cylinder body 2 for guiding the slide table 3.
A pair of adjustment bolts 7a, 7b spaced a certain distance from each other is mounted on one side of the slide table 3 near the piston rod 4 for finely adjusting the displacement of the slide table 3. A stopper block 8 which is in the shape of an elongate rectangular parallelepiped is fixed to the upper surface of the cylinder body 2 for limiting the displacement of the slide table 3 by engaging the adjustment bolts 7a, 7b.
When air is supplied under pressure into the cylinder body 2 through a port (not shown) defined in one side of the cylinder body 2, the piston is pushed in one direction to cause the piston rod 4 to displace the slide table 3 in the direction indicated by the arrow X. When air is supplied under pressure into the cylinder body 2 through another port (not shown) defined in one side of the cylinder body 2, the piston is pushed in the opposite direction to cause the piston rod 4 to displace the slide table 3 in the direction indicated by the arrow Y. In this manner, the slide table 3 can be linearly displaced in the direction X or Y along the linear guide 6.
The adjustment bolts 7a, 7b and the stopper block 8 are exposed on the upper side of the actuator 1. Therefore, foreign matter tends to be put between the adjustment bolts 7a, 7b and the stopper block 8. If some foreign matter is placed between one of the adjustment bolts 7a, 7b and the stopper block 8, the slide table 3 may not move properly the full reciprocating stroke when it approaches a terminal end of the range of displacement thereof.